Divided-central telephone system.



PENTEB MAR. 24, 19GBs W. WL BEAN. EVIDED GNRAL TELEHGHE SYSTEBLL-APLIUATZGN PILEO JUNE 15. 1.903.

Mm z

Aim

UNITED sTATEs PATENT oEEIcE.

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGG SWITCRBOARD &SUPPLY COMPANX, 0F CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

DIIIDED-.CETRAL TELEPHONE SYSTEM.

No. sse-3,093.

Specification of Letters Patent.

Patented March 24, 1908.

Application led June 15, 1903. Serial N o. 161,531.

To all whom it may concern.'

Be it known that I, WILLIAM W. DEAN, a citizen of the United States ofAmerica, and resident of Chicago, county of Cook, and State of Illinois,have invented a certain new and useful Improvement in Divided-CentralTelephone Systems, of which the following is a specification.

My invention relates to tele hone systems of the divided central type. nthis class of systems, the lines are each provided with slgnals upondifferent divisions ofthe switchboard and the subscriber is furnishedwith means for selectivelyl operating the said signals. By y thus beingable to call the different sections of the switchboard, the multiplejacks for eachfline need be placed upon `one only of said sections,whereby a' considerable reduction in the .multiple in-l stallation overthat of the straight multiple board is secured.

My invention has for its objects to provide a system of this type whichshall be comparatively simple and which operates wholl y current from acentral oflice and in whic the call res onsive devices in the severalsections of the board for each line are-oper'- ated by means ofsignaling currents of different strengths and. controlled front asubscribers station.

My inventionv is illustrated by the aid of the accompanying drawing inwhich f Figure 1 is a diagram of a telephone system embodying myimprovements. Fig.. 2 shows one wayof arranging the contacts of the linerelays of my-invention. 'l f L- indicates a subscribers telephone lineextendin in two limbs 2and 3 from the substation tothe central oiiice.At the substation an ordinary bell 4 and a condenser 5 are included asusual in the permanent bridge ofthe line conductors while Va'transmitter 6 and receiver7 are located infav bridge of said conductors,whose normal discontinuity is maintained by the switch hook `8 ,and thereceiver held thereby. This apparatus is adapted for use in connectionwith the common source of current located at the central oflce andtypifies any desired subscribers outfit.'

At the central 'oice the line is provide upon the four divisions of theswitchboar with answering jacks J, line signals S and a suitable pilotsignal S2. Upon one ofthe divisions of the switchboard, division C inthe case of line L shown in the drawing, multiple jacks J2 and J3, inany number, are rovided, Each line is also rovided with our line relaysR, R2, R3 an R4, and a cut-off relayer1 which, when operated, serves tosever the rela s and signaling apparatus from the externalyline circuit.and to connect the spri jacks of the switchboard with said externllline circuit for conversational urposes. In the normal extension 9 ofthe' lline conductor 2 are located the linerelays R and R4, the form'erhaving an actuating winding of greater resistance than the latter, 200and 100 ohms respectively having been found` satisfactory, saidconductor being connected by conductor 10 through normal contacts of therelay R4 thence by conductor 11 throughv normal contacts of'relay R andlikewise by -j oined to a wirel -1 5 including the high and low iresistance actuating windings of line relays R2 and R3 and which wire islikewise joined by conductors 10, 11, 12, 13 and 14 with said battery.The said line relays are suitably provided with locking windings tomaintain the same actuated after once being energized. At the substationfour keys, a, b, c,

and d are provided, the keys aand b being adapted to close the oppositeline-conductors through a high resistance 16 to ground, while the keysc' and d close the said conductors through low resistance or directly toground.

The cord circuit for establishing connections with the lines, and withwhich each operator at the'several sections is provided in anyn numberdesired, each includes an answerin plug P and a calling plug P2 havingtip an sleeve contacts ada ted to register with the like contacts of t ejacks ofthe telephone lines, the tip contact-s of said,

plugs being-connected by the strands t and t2 and the interposedcondenser c, while 'the sleeve contacts are similarly .connected by thestrands .s and s2 and the interposed condenser c2. Across the answeringend of the cord circuit supervisory relays r3 and r together with thecommonbatte B are con; nected, said relays controlling t ough their 'lam' adapted to be connected across the cord circuit by means of anysuitable listening key,

while the ringing generator is ada tend to be connected with the cordcircuit or ringing the wanted subscriber. I

' Assuming that the subscriber E wishes to call a subscriber whosemultiple jacks are located upon the division A, he presses the key a athis station, thus completing a path for current from the battery B atthe central oflice, over conductors 14, 13, 12, 11, 10, 9 and 2, andthence through the high'resistance 16 to ground. Owing to the presenceof the high resistance 16 in this path, the current is sufficient tooperate only the high resistance relay R, the low resistance relay R4remaining unoperated. The operation of'rel lay B, closes a local circuitfrom the .battery B over conductor 14 to junction point 19,

thence over conductor 20, spring l21 and ifnormal contact of relay B4,conductor 22, spring 23 and forward contact of relay B,

' subscriber releases his push button.-

thence through the locking winding of relay B and over conductor 24through the line lamp and the pilot relay for the operators Qposition',and thence by way of conductors 25 and 26 and through the normal contactand s ring 27 of cut-'od .relay 1" to ground. The line lamp and thepilot relay are actuated over this circuit and the line relay R islocked so that it is not denergized when Ttle local circuit at spring 23of relay R. must obviously be completed before the circuit through theouter spring is opened, as shown in Fig. 2. Said ligure shows a forni ofline relay having the superposed contacts mounted thereon, arranged sothat the forward set of contacts will be made before the back set ofcontacts is broken. The relay coils are woundv upon the spool 50 whichcarries an angle armature 51 adapted to rock upon the edge of themagnetic structure as shown. When the lower projecting end of the armature is attracted it will be noted that the con tact s rings will beactuated by the other end o said armature' as described with referenceto the line relays shown in Fig. 1. The same is true of all the otherline relays. v

lf the subscriber whose multipleA jacks are located upon the B sectionof the switchboard is wanted, the subscriber pushes key l) with theresult that line relay R2 which is of high resistance is operated in themanner just described with reference to the relay B connected with theother side of the line, the low resistance relay B3 remaininginoperative. The path for current in this instance The voperatorsreceiver 17` @sacas is the same as that traced for the relays over theother side of the line except that it is over` the other line conductor.The actuation of this line relay closes a local circuit over theconductor 14, through spring 28 of relay R3 and its back contact,conductor 29, spring 30 vand forward contact of relay R, the lockingwinding of said relay, conductor 31 and thence through the line lamp Slocated upon the B` division of the switchboard,4

through the pilot relay, andby way of conductors 25 and 26 to ground asbefore. The relay Rlfis thus locked and the signal located upon the Bdivision of the switchboard is operated. ln a similar manner thedepression of key c at the substation serves to closethe line conductor3 through a low resistance path to central with the result that bothrelays R2 and R3 in that line conductor are actuated, the currentflowing the same as before traced except that instead of passing throughthe high resistance in the substation it is now directed through the lowresistance path. The operation of the relay B3 closes a ocal circuit omthe conductor 14 through spring 28 of said relay and its forwardcontact, the locking winding of the said relay, conductor 33 to the lampS located upon the C division of the switchboard and thence by way ofcommon conductors 25 and 26 to ground. In the same manner the operationof key d at the substation operates the low resistance vrelay R4 overthe line conductor 2, the local circuit for the lamp in this instanceincluding the conductor 20, the locking winding of said relay andconductor 34 leading to the line lamp located upon the D division of theswitchboard.

Assuming that the signal upon the C division has been operated, theoperator inserts the calling plug P of her cord circuit, therebypermitting current to flow from the battery B over the sleeve strand ofthe cord circuit and the sleeve conductors 35, 36 and 37 of theswitchboard section of the line andthrough the winding of the cutoffrelay r to ground. This operates the cut off relay which severs theconnection with conductors 9, 10 and 15 and connects the line conductors2 and 3 with the said switchboard' section. Likewise the-local circuitsfor the lamps are opened at the said cut-off relay to render theminoperative. (Dwing to the fact that the subscriber has taken up histelephone the tip relay r2 is actuated by current flowing over themetallic line so that the supervisory 1' his response the tip superviso`is idle, said ring is connected with ground through the cut-off relay,and since the tip of the said plug is likewise` grounded no iiow ofcurrent results and no click is received.

5 When the line is busy, however, said test ringsare connected with thelive pole of one of the central batteries so that when the testing plugis brought into engagement therewith acurren't flows over the tip strandand a 1 0 surge of current takes place through the 'operators receiver.vAssumix'igthat the line is found idle, the plug is inserted in one ofthe multi le jacks of the called subscribers line and t e ringing keysprings 40, 40 depressed.

y The'generator 18 sends ringing current out overfthe telephone line,the return path for which'iscompleted throughthe central bat-.

l tary -l 3`..,"the auxiliary path 41 being completed around'thesupervisory relay 1*5 by the 'sleeve spring ofthe ringing key. Thecurrent from Vthe battery B serves to maintainthe cut-offv relay of thecalled line actuated duringrin "Y" After the subscriber has beencalled'but before his response, the rela 1.5 is actuated j to' close theocnl circuit o a supervisory P'signal S, which is lighted lto indicatethat the subscriber has not yet responded. Upon 3 so vactuated andserves to open sai supervisory signalcircuit whichrenders the same inertduring conversation. The batteries B and B furnish current to theconnected lines .for conversation, and for `the operation of the variousrelavs and signals associated therewith. At the termination of theconversation, the return of -thesubscribers receivers to their hooksdenergizesA the tip superviso relays r and r which closes the local 40circuits of lamps S and Ss which are lighted to indicate .to theoperator that the conversation has terminated. Upon observing this theoperator takes down the connections and returns all parts to normalposition.

4I claim:- 1. ln a telephone system,'the combination with a telephoneline having a plurality of connection terminals located u on theditferent'divisionsof a divided centra switchboard, Vof asignal for theline upon each division of said switchboard, cord circuits at each ofthe divisions ofthe switchboard to establish connections with the linethrough the medium of said connection terminals for 56 conversationalpurposes, a common source of current at the central oflice adapted to beconnected with the telephone line by means of said cord circuits tofurnish current over the line for talking, and means cont-rolled 60 fromthe substation for causing currents of different strengths to flow fromsaid source over the telephone line to selectively operate said si nalsupon the various divisions of the switch oard, substantially asdescribed.

2. In a telephone system, the combinarelay -1'4 is tion with a telephoneline having a plurality `vof connection terminals located upon t-hedifferent divisions of a divided central switchboard, of a. signal forthe line upon each division of said switchboard, cord circuits ateach ofthe divisions of the switch-board various divisions of the switchboard,substantially as described.

3. In a four-division, divided central telephone circuit, thecombination with a tele- 'phone line, having a connection terminal iupon each of the four divisions of the switchboard at the centraloiiice, a signal for the line in each of said divisions of theswitchboard, cord circuits at each division of the switchboard toestablish connections with -the telephone line through'the mediumof saidlconnection terminals for conversational purposes, a. common source ofcurrent at the central office associated with said cord circuits adaptedwhen a connection exists at any of said divisions to furnish currentover the line for talking, 4two of said signals being connected witheach line conductor of the telephone line, and means at the substationto cause current of different strengths to flow from said source overeitherV of said line conductors to selectively operate the signalsconnected therewith, substantially as described. y

4. ln a telephone system,the combination with a telephone lineterminating in connection terminals upon the various divisions of adivided central switchboard, of a plurality of signals for the line-oneupon each of said divisions, a central common source of current, aresistance at .the substation of the line, and meansunder the con- 'trolof the subscriber to close circuits from said central source over thetelephone line and to at will include or exclude said resistance tothereby selectively operate said signals, substantially as described.l

5. ln a telephone system, the combination with a telephone line, of a.plurality of signals therefor located upon the diiierent divisions of adivided central switchboard, a central common source of current, a relayat the central office connected with the line foreach of said signalfandserving to control the same, said relays being responsive to currents ofdiiierentfstrengths, and means at the substation for causing currents ofdifferent strengths toilow over the line from to establishconnectionswith the line through telephone -line from said common source toselectively operatevv said signals upon the said source and selectivelyoperate said relays .means to cause said signals to selectively respondto the .currents over said different paths, substantially as described.

7. In a telephone system, the combination with a telephone line, of aplurality of signals therefor located upon the different divisions of aswitchboard, a central source of current, means at the substation forclosing diiierent paths Jfor current and of. diiierent resistances overthe telephone line, means to cause said signals to selectively respondto such different currentsand a cut-oil' relay for the line actuatedwhen connection is established therewith, at any of said divisions torender said signals inoperative, substantially as described 8. In atelephone system, the combination with a telephone line, of a pluralityof signals therefor located upon the diierent divisions of adividedcentral switchboard, a central common source of current, a relayat the central oflice connected with the line for each. of said signalsand serving to control the same, each of said relays having twowindings, one of said windings of each of. said relays being responsiveto currents of diier-v ent strengths and being adapted toenergize saidrelays when a subscriber calls central, the other winding of each ofsaid relays being in the circuit of the corresponding signal, andconstituting a. locl'ing winding for said relays, and means at thesubstation for causing currents of different strengths to iiow throughsaid'first mentioned windings from said source to selectively operatesaid relays, substantially as described.

9. Ina telephone system, the combination with a telephone line, of aplurality of signals therefor located upon the different divisions of adivided central switchboard, a central common source of current, a pairof relays at the central oiiice connected with each line conductor andadapted to control the circuit of said signals, the relaysassociated itheach line conduct-or being responsive to currents of dierent strengths,a resistance atL th'e substation, andineans for including or eirclh'dingsaid resistance from the circuit of ths/ relays associated witheitherot` said line conductors, 'whereby saidrelays are selectivelyenergized by current from said source and the corresponding signalselectively controlled, substantially as described.

10. In al telephone system, the combination with a telephone line, of aplurality of signals therefor located upon the dierent divisions of adivided central switchboard, a central common source of current, aplurality of relays at the central office connected with the line forselectively controlling said signals, each of said -relays having twowindings, one of said windings ofv` each relay being responsive tocurrents of different strengths, means at. the substation for sendingcurrents of different strengths over the line to selectively energizesaid .windings, normally-closed contacts for lsaid lrelays in the pathof current through said winding, the vvother winding of eachrelayconstituting '.a locking winding therefor, nbrmally-open contacts foreach relay in the path of current through said locking windings, andmeans for maring said last men-- tioned contacts before saidiirstmentioned. contacts arel broken, whereby said locking winding maintainssaid relay energized after the selective calling current is'broken andt/he corresponding signal remains exposed," substantially as described.

11.- In a telephone system, the combination with a telephone line, of aplurality of signalsltherefor located upon the different divisions of aswitchboard, relays at thecentral oiiice associated with said signals, acentral source of current, l,means at the subvstation of the line forclosing diHerent paths of different resistances over the telephone lineand through the windings of aV plurality of said relays in series fromsaid source, and means to cause said signals to selectively respond, tothe currents over said different paths, substantially1 as described.`

Signed by me at Chicago, county of Cook and State of Illinois, this 12thday of June 1903.

WILLIAM W. DEAN.

